Water is a substance without colour, smell or taste and without which life on earth would be impossible. Drinkable water and rivers contain different substances; quantity and sort of the latter differs regarding the region of the source of water, chemical structure of the ground on which and through which it flows. Water hardness is caused mostly by hydrogen carbonates, calcium and magnesium ions. The greater the quantity of those dissolved in natural water from the soil and rocks, the harder it is. In the first part of my diploma thesis I determined water hardness with rapid test and titration of drinking water. I determined carbonate hardness, total hardness and calcium hardness and then compared the results. In the following part of my study I determined water hardness in samples from different rivers in Slovenia. Next to rapid test and titration, a comparison based on atomic emission spectrometry was carried out on the water samples from river Sava and Lesji potok. Next to calcium hardness I also checked magnesium water hardness. In the last part of my study I used method of leaching with a solution of ammonium acetate to determine calcium hardness in the soil or calcium concentration is soil.
Methodological part of my diploma thesis is based on the syllabus of the 8th grade of primary school. Pupils would get acquainted with laboratory work and hardness of the water with the use of rapid test and water titration. Since the necessary equipment and chemicals used for the implementation of experiment do not represent any hazard, pupils could work in pairs.
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